Previously, many different and varied hacksaws have been in use utilizing thin hacksaw blades that are employed mostly for cutting metal and hard material. Generally speaking, this type of saw may be grouped as a keyhole type, as the blade is made to be extended and does not utilize a connection on both ends through the holes provided as in the more conventional styles. Further, the blade may be extended in a unsupported manner making the blade provide its own structure. The more conventional type, tensionsthe blade taute between the ends with structure therebetween. Many attempts have been made to make the keyhole type practical, some completely unsupporting the blade, and others attaching the blade compressibly on the end.
A search of the prior art did not disclose any patents that read directly on the claims of the instant invention however, the following U.S. patents were considered related:
______________________________________ PATENT NUMBER INVENTOR ISSUED ______________________________________ 3,756,298 West 4 September 1973 3,447,580 Keymer 3 June 1969 2,966,931 Dreier 3 January 1961 2,920,668 Leist 12 January 1960 2,331,638 Taylor 12 October 1943 ______________________________________
West teaches a single one piece construction that utilizes a tensioning screw on an elongated end, with the blade projecting through the handle portion.
Keymer discloses, a tool that is very similar to the above except the handle and arm are separate elements, with the arm formed of two parts.
Dreier does not retain the blade with his wedge shaped sheath, instead it is contained within the wedging shape, pressing the blade into the cavity when in use, with pressure on the blade. Retension is made with a threadable compression ring clamping the blade into the handle by tightening the ring.
Leist uses two separate halves of a handle having a pistol grip. In one embodiment, the blade is tensioned using the hole in the end of the blade with an angular arm for support.
Finally, Taylor teaches a one piece construction with a hollow tubular handle, and, a split two piece finger with a screw clamping the pieces together.
It will be seen that the prior art has approached the problem of attaching the blade with a screw at the end of the arm, wedging it into a full length sheath, or utilizing the hole in the end of the blade. This method does not provide for firmly grasping the blade as only a small area is in contact with the blade.
For background purposes and as indicative of the art to which the invention relates, reference may be made to the remaining cited patents.
______________________________________ PATENT NO. INVENTOR ISSUED ______________________________________ 2,490,094 Rogers 6 December 1949 DES 246,416 Schmidt 22 November 1977 DES 228,225 West 28 August 1973 DES 207,247 Reuterfors 21 March 1967 ______________________________________